1. Technical Field
The present disclosure relates to a light-emitting device, and in particular to a light-emitting device comprising an intermediate layer which is bonded to a substrate through a transparent bonding layer and which has a refraction index between the refractive index of the substrate and the refractive index of a semiconductor window layer.
2. Description of the Related Art
The light-emitting diodes (LEDs) of the solid-state lighting elements have the characteristics of the low power consumption, low heat generation, long operational life, shockproof, small volume, quick response and good opto-electrical property like light emission with a stable wavelength, so the LEDs have been widely used in household appliances, indicator light of instruments, and opto-electrical products, etc.
Recently, a light-emitting device with a flip-chip package structure having light emitted toward the substrate is developed. However, how to improve the light-emitting efficiency of the light-emitting device is still an important issue in this art.